Packaging method and apparatus

ABSTRACT

A packaging system wherein a web of interconnected heat-sealable bags are successively fed to a loading station where the bags are opened by an improved air flow system and loaded. An improved sealing and detaching assembly grips a loaded bag and isolates a region of the bag where a heat seal is to be formed from external forces thereby (1) permitting the formation of a heat seal in bag portions which are relaxed and, therefore, not subject to tearing or distorting, and (2) permitting the assembly to pivot relative to the web to tear off a loaded bag at the same time a heat seal is being formed on the bag. The assembly includes an improved resilient closure bar which, during a forward stroke of travel (1) engages one face of a loaded bag, (2) closes the bag, (3) clamps the opposite bag face against a pair of spaced gripper bars which isolate a region of the bag for heat sealing, and (4) brings the isolated region into contact with a heater bar to effect a heat seal. The gripper bars are spring mounted and biased to a position forward of the heater bar to effectively isolate a region of the bag for sealing prior to seal formation.

REFERENCE TO RELATED AND RELEVANT PATENTS AND APPLICATION

The present application is a division of application Ser. No. 336,560filed Feb. 28, 1973, now U.S. Pat. No. 3,965,653, and acontinuation-in-part of parent application Ser. No. 139,453 filed May 3,1971, now U.S. Pat. No. 3,815,318.

Flexible Container Strips, U.S. Pat. No. 3,254,828 issued June 7, 1966to Hershey Lerner. This patent will be referred to as the ArticlePatent.

Mechanism for Automatically Feed, Loading and Sealing Bags, U.S. Pat.No. 3,477,196 issued Nov. 11, 1969 to Bernard Lerner. This patent willbe referred to as the Machine Patent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to packaging and more particularly to animproved packaging system for opening, loading, closing and sealingbag-like containers at a loading station and for isolating the forceapplied to a loaded container as it is severed from the remainder of theweb along a preformed line of weakness.

2. Prior Art

The referenced Article and Machine Patents relate to the utilization ofa packaging web comprising a chain of interconnected bags. The bags areeach open on one face. The other face of each bag is connected to acontiguous bag along a preformed line of weakness.

The Article Patent describes a simple mechanism for dispensing, openingand loading the interconnected bags. A coiled web of interconnected bagsis positioned on a mandrel in a carton. A blower is coupled to thecarton to provide a positive pressure within the carton. The bags arefed, closed end first, through a slot in the carton. As the bags emergefrom the carton, they are inflated by a relatively gentle flow of airemitted from the slot due to the positive pressure in the carton. Aproduct is inserted in the inflated bag. The operator then moves the webuntil the next bag emerges from the carton and inflates, and alsoseparates the loaded bag for a sealing operation.

The Machine Patent describes a machine for dispensing, loading, sealing,and severing the bags in sequential automatic operations. In addition,the machine is adapted to be connected to automatic counting andconveying equipment so that products being packaged are allautomatically measured and deposited in the bags as the bags are fed toa load station. The Machine Patent also describes a system for providingan interrupted heat seal line whereby heavily loaded bags are not soweakened during the heat sealing operation that they tear along thesealing line.

These two described systems represent a system which is relativelysimple, but slow, and a system which is relatively complex, but fast,for dispensing, loading and sealing bags. The optimized system for anygiven packager depends on a number of variables such as the size andnature of the products being packaged, the number of packages of anygiven product or group of products required, and the total number ofpackages, that is the total packaging rate, of the packager.

In the past, the most commonly used system for dispensing, separatingand sealing bag-like containers has been basically manual. A machinesimilar in appearance to that shown in the Machine Patent has been themost commonly used. With this commercially successful arrangement, a webof bags is mounted on a mandrel within a housing. The web is fed throughan exit slot near the top of the housing and then downwardly until anopen bag is at a load station near the top of the machine and near theexit slot.

In use, the operator deposits the product to be packaged in the open bagat the load station. The operator then grasps the loaded bag, pulling itdownwardly until the next bag is at the load station. The loaded bag isthen manually severed and the open end is inserted between the jaws of aheat sealer provided near the base of the housing. The jaws are thenactuated to close and effect a sealing of the bag. After a predeterminedtime interval, when a seal has been effected, the jaws will openallowing the bag to drop into a box or other receptacle beneath themachine.

The referenced parent application describes a novel packaging system foropening, loading, closing and sealing bag-like containers at a loadingstation. Relatively movable gripper and closure bars clamp a loadedcontainer to isolate the forces applied in separating the loadedcontainer from a web. The container can be heat sealed substantiallyconcurrently with the separation. Alternatively, the loaded containerscan be separated from the web without being sealed, or can be sealedwithout being separated from the web to produce a chain ofinterconnected loaded bags.

The apparatus described in the referenced parent application includes aheater bar and a sealing bar which are movable toward and away from eachother to clamp and heat seal a loaded container. A gripper bar isrigidly mounted above the heater bar. The gripper bar cooperates withthe sealer bar to grip the packaging web in regions between the heatseal line and a preformed line of weakness in the web. The gripping barisolates the heat seal line from forces applied to the web to sever theloaded container from the remainder of the web.

Another apparatus feature described in the referenced application is atear-off mechanism for severing a loaded container from the remainder ofthe web serially along a preformed line of weakness from one side of theweb to the other. The heater bar, the sealer bar and the gripper barform part of a tear-off assembly which is pivotally mounted about anaxis on one side of the web. The tear-off assembly is power driven toeffect a sharp and rapid tear-off movement. This rapid tear-off movementnot only serves to rapidly sever the loaded container from the remainderof the web but also serves to reduce the effective force imposed on theheat seal line by the weight of the product being packaged.

The heater bar described in the referenced parent application is a bluntmember covered with TEFLON to prevent sticking. A spring biased stripperbar is provided to effect a positive removal of the sealed loadedpackages from the heater bar.

SUMMARY OF THE INVENTION

The present invention relates to an improved packaging system featuringan improved air flow system for opening bag-like containers at a loadstation and an improved closure and gripping assembly for isolating aregion of the web from external forces.

In accordance with one feature of the present invention, an improved airflow sytem is provided for opening bag-like containers at a loadingstation. A tubular conduit is provided near the loading station todirect a narrow stream of high velocity pressurized air at a containeras it arrives in the loading station. This high velocity air stream ispreferably delivered in a brief burst of about one-tenth second inlength and augments the conventional relatively gentle air flow currentto assure that each and every bag is opened at the loading station. Thehigh velocity air stream is concentrated in a limited area of the openend region of the container.

In accordance with another feature of the present invention, an improvedclosure and gripping system is provided including a pair ofspring-mounted gripper bars which effectively isolate a web regionbetween the gripper bars from external forces. These gripper bars can,in one application, be used to isolate a web region containing an easilyopened tear-seal while the container is being severed from aninterconnected web. In another application, the gripper bar can bepositioned one on either side of a heater bar to isolate the region ofthe heat seal from forces on both sides of the heat seal. The gripperbars are preferably biased to a position forward of the heater barthereby enabling them:

1. To isolate a region of the container prior to the time when heatsealing is begun; and,

2. To function as strippers to effect a positive removal of the sealedloaded container from the heater bar, whereby no additional strippingmechanism is required.

The apparatus of the referenced parent application has a single gripperbar secured adjacent the heater bar at a position above the heater bar.The gripper bar is provided with a finned heat dissipator to keep itcool. The present invention eliminates the need for the heat dissipator.One reason the gripper bars of the present invention do not becomeexcessively heated is because they are not mounted immediately adjacentthe heater bar, but rather are mounted on a movable carriage and arenormally biased to a position forward of the heater bar.

Another reason the gripper bars do not become excessively heated isbecause a sheet of TEFLON is provided extending across the heater bar.The end regions of the TEFLON sheet are supported on rollers on oppositesides of the heater bar with an intermediate portion of the sheetextending across the heater bar. This sheet not only prevents containersbeing sealed from sticking to the heater bar but also serves to directair which has been heated by the heater bar away from the region ofoperation of the gripper bars.

In order to assure proper operation of the apparatus of the referencedparent application, it is necessary to carefully position the singlegripper bar relative to the heater bar. If the gripper bar extends toofar forwardly of the heater bar, it will interfere with sealing. If thegripper bar does not extend forwardly of the heater bar by a properamount, it will not effect a sufficient engagement with the web toisolate separation forces from the region of the seal. The presentinvention obviates the need for precise gripper bar positioning byspring mounting the gripper bars so that they are biased into engagementwith the web as the web approaches the heater bar. The gripper barsengage the web before the web reaches the heater bar, and then travelwith the web as it approaches the heater bar.

Since the gripper bars are located substantially forwardly of the heaterbar and make operative engagement with the web before the web is broughtinto contact with the heater bar, web severance along a preformed lineof weakness can be initiated before seal formation has even begun. Thispermits a faster sequence of packaging operation.

The heater bar of the referenced application was preferably saw-cut ornotched at spaced intervals along its length to provide an intermittentheat seal whereby the minute unsealed regions along the seal retaintheir strength during the sealing operation to hold the web together.The present invention obviates the need for the formation of thesenotches in the heater bar. Since the dual gripper bars fully isolate theregion of the heat seal from such external web forces as the weight ofthe contents within the bag, the seal is effected in a fully relaxedregion of the web. The notched heater bar can, of course, still beoptionally used as a safeguard to positively prevent web severance.

Accordingly, it is a general object of the present invention to providea novel and improved packaging system.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an automatic packaging machine constructedin accordance with the present invention;

FIG. 2 is a sectional elevational view as seen from the plane indicatedby the line 2--2 in FIG. 1;

FIG. 3 is a sectional elevational view as seen from the plane indicatedby the line 3--3 in FIG. 1; and

FIG. 4 is an enlarged sectional elevational view of a portion of themachine shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 3, a packaging machine constructed in accordancewith the present invention is shown generally at 10. A pair of idlerrolls 13, 14 are supported by the cabinet 11. A packaging web 12 ofinterconnected bag-like containers is fed vertically upwardly from astorage region, not shown, formed in the lower portion of the cabinet11. The web 12 is reeved over the idler roller 13 and extendshorizontally from the roller 13 to the roller 14. From the idler roller14, the web 12 is directed forwardly and upwardly by a guide bar 15toward a pair of feed rolls 16, 17.

The upper feed roll 16 is rotatably mounted within the cabinet 11 and isdriven by a motor 26. A pair of bearings 22, 23 journal the feed roll 16for rotation. A pair of brackets 24, 25 secured to the cabinet 11support the bearings 22, 23. A bracket 27 mounts the motor 26 within thecabinet 11. The motor 26 has an output shaft 28. A drive pulley 29 ismounted on the output shaft 28. A driven pulley 31 is secured to theupper feed roll 16. A drive belt 30 is reeved around the pulleys 29, 31to rotate the upper feed roll 16 concurrently with the output shaft 28.

The lower feed roll 17 is rotatably carried by a pair of arms 40, 41which are pivotally mounted within the cabinet 11. A pair of bearings36, 37 journal the feed roll 17 for rotation. A pair of brackets 38, 39support the bearings 36, 37. The brackets 38, 39 comprise outer endregions of the arms 40, 41. The arms 40, 41 extend rearwardly from theregion of the feed roll 17 and are pivotally mounted within the cabinet11 by pivotal connections 42, 43.

The pivotal mounting of the arms 40, 41 permits the arms to be pivoteddownwardly to separate the lower feed roll 17 from the upper feed roll16 to facilitate feeding of the web 12 between the rolls 16, 17. A pairof threaded lock bolts 44, 45 releasably secure the arms 40, 41 in theirupper position where the feed rolls 16, 17 are in operative engagementwith the web 12. The lock bolts 44, 45 extend through apertures formedin the brackets 38, 39 and into threaded apertures formed in thebrackets 24, 25. The lock bolts 44, 45 are provided with knurled heads46, 47 to facilitate their manual rotation.

Removal of the web 12 from the feed rolls 16, 17 during web feeding isfacilitated by a series of reduced diameter portions 20, 21 whichseparate larger diameter feed roll portions 18, 19 one from another.Projecting fingers 21a formed integrally with a bar 21b extend into thereduced diameter portions 21 to strip the web 12 off the feed roll 17.

From the feed rolls 16, 17 the web 12 is fed downwardly along asubstantially vertical path of travel to a loading station, indicatedgenerally by the numeral 50 in FIGS. 2 and 3. A loading chute 51 isprovided for discharging parts 52 into a bag 53 positioned in theloading station 50.

In order to open the container 53 when in the loading station, a blowerindicated generally by the numeral 54 is provided within the cabinet 11.A vertically extending duct 55 connects with the blower output duct 56.The vertically extending duct 55 is disposed adjacent one side of thecabinet 11 and serves to duct air from the blower 54, which is disposedbeneath the web 12, to the region above the web 12. A horizontallyextending duct 57 connects with the vertically extending duct 55 anddischarges air from the blower 54 into the region above the web 12. Arelatively gentle flow of air is thereby caused to flow over the upperfeed roll 16 and downwardly along the surface of the web 12, asindicated generally by the arrows 58. This gentle air flow is normallysufficient to separate the faces of a bag and open the bag. On occasion,however, the bag faces may tend to adhere together. In accordance withone feature of the present invention, an auxiliary air flow system isprovided to supply a brief burst of high velocity air to assure that thebag faces separate to permit opening of the bag by the describedrelatively gentle flow of air. The auxiliary air flow system includes atubular conduit 200 of approximately one-fourth inch inner diameter. Theouter end 201 of the conduit 200 terminates above the loading station 50to direct a high velocity burst of air toward the upper unsealed end ofthe bag positioned in the loading station. The inner end 202 of theconduit connects with a solenoid valve 203. A pressurized air conduit204 supplies air to the valve 203. Electrical circuitry, not shown, isprovided to energize and open the valve 203 to deliver a burst of air ofshort duration, typically one-tenth second, to initiate separation ofthe bag faces.

A sealing and detaching structure is provided for sealing a loaded bagand for separating the loaded bag from the web 12. To these ends, asubstantially vertically extending guard bracket 60 is providedrearwardly of the path of travel of the web 12 adjacent the loadingstation 50. A slot 61 is provided in the guard bracket 60. A heater bar62 is positioned within the region of the slot 61. A pair of gripperbars 63a, 63b, having forwardly facing edges 163a, 163b are positionedforwardly of the heater bar 62 along opposite sides of the slot 61.

The slotted guard bracket 60 serves a number of functions. First, itacts as a safety device to prevent injury to the fingers or hands of anoperator by shielding the heater bar and the knife bar from contact.Second, it facilitates stripping of sealed containers from the heaterbar and the sealer bar. Since the portion of the web being sealed mustassume a generally U-shaped configuration upon insertion through theslot 61, the weight of the loaded bag will tend to pull the bagoutwardly and away from the heater bar and sealer bar at the completionof the sealing operation.

Referring to FIG. 4, a carriage block 175 supports the gripper bars 63a,63b. The carriage block 175 is rectangular in cross-section. A V-shapedslot extends through the block 175 defining upper and lower inclinedsurfaces 176, 177. Threaded fasteners 174 extend through aperturesformed in the gripper bars 63a, 63b and into the carriage block 175 torigidily secure the gripper bars 63a, 63b to the block 175.

The carriage block 175 is movably supported on the guard bracket 60.Threaded fasteners 180 extend through apertures 181 formed in thecarriage block 175 and are threaded into apertures 182 formed in theguard bracket 60. The apertures 181 have enlarged inner end regions 181awhich are of sufficiently large diameter to receive compression coilsprings 183. The outer end regions 181b of the apertures 181 are of suchdiameter as will permit the carriage block 175 to slide freely along thefasteners 180.

The springs 183 bias the carriage block 175 forwardly toward a positionof engagement with the guard bracket 60. Each of the springs 183 ispositioned around a separate one of the fasteners 180. One end of eachspring 183 engages the head of its respective fastener 180. The otherend extends into the bore 181a and engages the block 175 in the regionof transition between the enlarged bore 181a and the reduced diameteraperture region 181b.

The movable carriage block 175 serves to mount the gripper bars 63a, 63bfor movement relative to the heater bar. The described spring-biasedmounting system serves to bias the gripper bars toward a positionforward of the heater bar 62. When the carriage block 175 is inengagement with the guard bracket 60, the outer edges 163a, 163b of thegripper bars protrude partially into the guard bracket slot 61. Fromthis forwardmost position, the gripper bars 63a, 63b are movablerearwardly to a position wherein they are substantially aligned with theedge 162 of the heater bar 62. The gripper bar edges 163a, 163b arepreferably pointed in cross-section, but may, instead be toothed alongtheir length in the manner of a hacksaw blade. The upper gripper baredge 163a preferably projects slightly forwardly of the lower gripperbar edge 163b to assure that the upper gripper bar effects a strong andsecure grip on the web. The upper gripper bar 63a preferably penetratesthe web slightly to assure a firm grip.

A closure bar 64 is provided for clamping the faces of the bag 53 intoengagement with one another with the inner face in engagement with theheater bar 62 and the gripper bars 63a, 63b. A resilient pad 65 iscarried by the closure bar 64 to perform this clamping function.

The closure bar 64 comprises a cross member 164 supported on a pair ofrods 66, 67. The rods 66, 67 extend through apertures formed in thecross member 164 and are secured by nuts 165. The cross member 164 isL-shaped in cross-section, as best seen in FIG. 4, and defines anL-shaped recess 166.

The resilient pad 65 comprises a side-by-side assembly of forward,intermediate, and rearward members 167, 168, 169 which are adheredtogether by suitable adhesive. The forward member 167 is a relativelythin strip of silicone rubber which is sufficiently stiff to firmlypress the faces of the bag 53 into engagement with the gripper bars 63a,63b and the heater bar 62. The intermediate member 168 is a relativelythick, soft foam rubber strip which resiliently mounts the siliconestrip 169. The foam rubber strip 168 not only serves to uniformlydistribute the pressure exerted by the silicone strip 167 on the bag 53,but also serves as a safety device to prevent injury to an operatorshould his fingers be caught between the closure bar 64 and the guard60. The rearward member 169 comprises a steel strip which is positionedin the L-shaped recess 166 and secured by fasteners 170 to the crossmember 164. The fasteners 170 extend through apertures formed in themember 169 and are threaded into apertures formed in the cross member164.

A significant advantage of the described resilient closure bar is itsability to conform to the shape of a warped gripper or heater bar, andits ability to compensate for unaligned gripper and heater bars. Theresilient closure bar is thus quite tolerant of warped or misalignedheater and gripper bars and thereby significantly reduces machine downtime to correct such problems.

The support rods 66, 67 movably mount the sealing bar 64 for movementtoward and away from the heater bar 62 and the gripper bars 63a, 63b. Atransversely extending bar 68 and a pair of apertured brackets 69, 70slidably support the rods 66, 67. A transversely extending frame member71 rigidly connects the inner ends of the rods 66, 67. The outwardmovement of the rods 66, 67 is limited by the engagement of the framemember 71 with the brackets 69, 70.

A pneumatic actuation system is provided to extend and retract thesealing bar 64. A pneumatic cylinder 72 is connected between thetransversely extending bar 68 and the frame member 71. Extension of thepneumatic cylinder 72 effects rearward or inward movement of the sealingbar support assembly including the frame member 71 and the support rods66, 67. When the pneumatic cylinder 72 is fully extended, the resilientpad 65 is clamped firmly against the heater bar 62 and the gripper bars63a, 63b. Retraction of the pneumatic cylinder 72 effects forward oroutward movement of the sealing bar assembly.

When the sealing bar 64 is in its outwardly extended position, the web12 with its integrally formed container 53 extends between the supportrods 66, 67. The container 53 is then solely supported by its connectionto the web 12. When, however, the resilient pad 65 clamps both bothsides of the container 53 against the heater bar 62 and the gripper bars63a, 63b, the container 53 is supported by this clamping action. Theheater bar 62 then serves to heat seal the container 53 while thegripper bars 63a, 63b serve to isolate the region of the heat seal fromsuch web forces as might otherwise cause a tearing of the web duringheat seal formation.

Referring to FIG. 4, the heater bar 62 has a relatively sharp forwardlypointing sealing edge 162. A TEFLON sheet 160 is stretched across theedge 162. A pair of rollers 161 on opposite sides of the heater bar 62support the sheet 160. Opposite end regions of the sheet 160 are coiledon the rollers 161 permitting used sheet portions to be reeled onto oneof the rollers, and unused sheet portions to be reeled off the other ofthe rollers 161. In addition to preventing containers being sealed fromsticking to the heater bar, the TEFLON sheet 160 also serves to directheated air currents away from the region of operation of the gripperbars 63a, 63b, to prevent their becoming excessively heated.

When relatively heavily loaded containers are being sealed, it mayoptionally be desirable to provide an interrupted seal whereby the webis not weakened across its entire width during the formation of the heatseal. This may readily be accomplished by providing the edge 162 of theheater bar 62 with saw cuts at spaced intervals along its length toprevent the transfer of a sufficient amount of heat to the web at spacedintervals to effect a continuous uniform heat seal.

The sealing and detaching assembly, including the heater bar 62, thegripper bars 63a, 63b, the sealing bar 64, and the pneumatic actuator 72are all supported by a pivotally mounted frame structure. This framestructure includes a pair of side members 80, 81 connected at their rearends by a transversely extending frame member 82, and at their frontends by the bar 68. This frame structure is pivotally movable about anaxis located at the left side of the machine 10 as viewed in FIG. 3, andis movable between the up position shown in solid lines and the downposition shown in broken lines.

Referring to FIG. 1, a pair of brackets 76, 77 are formed integrallywith the arm 40. A shaft 75 is supported by the brackets 76, 77. A pairof collars 78, 79 are journalled on the shaft 75. The collar 78 issecured to a bracket 69 formed integrally with the frame side member 80.The collar 79 is secured to the bar 68.

As will be apparent, the frame assembly including the members 68, 80,81, 82, is pivotally movable about the axis of the shaft 75. Duringmovement of this frame assembly from the up to the down positionillustrated in FIG. 3, a loaded container which is clamped between thegripper bars 63a, 63b and the sealing bar 64 is severed from theremainder of the web 12. The pivoting action stresses the web in suchfashion as causes the web to sever serially along a preformed line ofweakness from the right side to the left side of the web as viewed inFIG. 3.

A pneumatic system is provided to pivot the sealing and detachingassembly about the shaft 75. Referring to FIG. 3, a pneumatic cylinder85 is secure at its upper end to the cabinet 11 and at its lower end toa bracket 86. The bracket 86 is connected to the side bar 81. When thecylinder 85 is extended, it pivots the sealing and detaching assemblydownwardly, and when the cylinder 85 retracts, it pivots sealing anddetaching assembly upwardly.

The operation of the machine 10 as described above is quite similar tothe operation of the system described in the referenced parentapplication and accordingly will not be described in great detail. Oncea bag 53 is advanced to the loading station 50 and opened as illustratedin FIG. 2, parts 52 are discharged through the loading chute 51 into theopen bag 53. The sealing bar 64 is then drawn inwardly to clamp bothsides of the container 53 into engagement with the gripper bars 63a,63b. Continued inward movement of the sealing bar 64 brings the sides ofthe container 53 into engagement with the mylar-covered heater bar 62.Once the container 53 has been engaged by the gripper bars 63a, 63b, thesecond actuator 85 is extended to pivot the sealing and detachingassembly about the shaft 75, to the dotted line position of FIG. 3. Thispivotal movement imparts a tearing action to the web which severs theweb along a preformed line of weakness above the region which isisolated by the gripper bars 63a, 63b.

Once a heat seal has been formed a bag tear off has been completed, thesealing bar 64 is retracted. The spring biased gripper bars 63a, 63bthen serve to strip the sealed container 53 off the heater bar 62,permitting the container to drop into an awaiting receptacle or hopper(not shown).

The sealing and detaching assembly, with the sealing bar in its extendedposition, is then returned by the second actuator 85 to its sealingposition. At the same time an electrical control means (not shown)operates the motor 26 to advance the web 12. As indicated previouslythis web advance can commence before the seal is completed and the pad65 has been moved to release its clamping pressure. By this arrangement,another container is fed toward the loading station 50 prior to andsimultaneously with the return movement of the sealing and detachingassembly. The container is then loaded and the sealing operationautomatically repeated.

As will be appreciated, during the formation of a heat seal, the gripperbars 63a, 63b fully isolate the region of the heat seal from forcesresulting both (1) from the weight of the parts 52 within the bag 53,and (2) from the tearing forces imparted during pivotal movement of thesealing and detaching assembly. Moreover, since the gripper bars arespring-biased into engagement with the web 12 before the web contactsthe heater bar 62, the tear-off action can begin even before heat sealformation has been initiated.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:
 1. A method of packaging comprising the steps of:a.positioning a portion of a plastic web including a container to besealed in a sealing station including a spaced pair of griper bars and aheater bar therebetween; b. isolating a part of the web to be sealedfrom external forces after the container has been loaded by bringing thegripper bars while in canted relationship into engagement with the weband clamping the web against the gripper bars; c. effecting a heat sealin such isolated part while such portions are clamped against thegripper bars; and, d. separating the container from the web while theweb is clamped to isolate said part, such separation being effectedalong a line of weakness in the web outside such isolated part by movingthe loaded container together with the heater bar and the gripper barsrelative to the remainder of the web to exert separation forces alongthe line of weakness.
 2. A method of packaging comprising the stepsof:a. providing a web of packaging material having an open, loadedcontainer; b. clamping portions of such container after it has beenloaded against a gripper means to isolate a part of such container fromexternal forces; c. operating a closure securing means to secure theclosure of such loaded container in such part while such portions areclamped against said gripper means; and, d. separating such loadedcontainer from the web along a line of weakness in the web spaced fromsuch part while the part is isolated by moving such container togetherwith the closure securing means and the gripper means relative to theremainder of the web to exert separation forces along the line ofweakness.
 3. The method of claim 2 wherein the procedure of effecting aseparation is begun prior to the securing of the closure.
 4. A method ofpackaging comprising the steps of:a. providing a web of packagingmaterial having a container, and positioning such container in a closurestation; b. directing a burst of relatively high velocity air towardsuch positioned container to initiate opening of such container; c.directing a relatively gentle stream of air toward such positionedcontainer to complete the opening thereof; d. loading such opencontainer; e. clamping portions of such loaded container against agripper means to isoalte a region of such container from externalforces; f. securing the closure of such loaded container in such regionwhile such portions are clamped by operating a closure securing means;and, g. while such portions are clamped against said gripper means,separating from such loaded container from the remainder of the webalong a line of weakness in the web spaced from such region by movingsuch container together with the closure securing means and the grippermeans relative to the remainder of the web to exert separation forcesalong such line of weakness.